-well-completion-planning
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-well-completion-planning


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by the completion design criteria.
Most obvious are the dimensional requirements deter-
mined by the selected completion tubulars and compo-
nents. For example, if a multiple string completion is to be
selected, an adequate size of production casing (and
consequently hole size) must be installed. Similarly, the
wellbore deviation or profile can have a significant impact.
Drilling and associated operations, e.g., cementing, per-
formed in the pay zone must be completed with extra
vigilance. It is becoming increasingly accepted that the
prevention of formation damage is easier, and much more
cost effective, than the cure. Fluids used to drill, cement or
service the pay zone should be closely scrutinized and
selected to minimize the likelihood of formation damage.
Similarly, the acquisition of accurate data relating to the
pay zone is important. The basis of several major deci-
sions concerning the technical feasibility and economic
viability of possible completion systems will rest on the
data obtained at this time.
A pre-completion stimulation treatment is frequently con-
ducted. This is often part of the evaluation process in a
test-treat-test program in which the response of the reser-
voir formation to a stimulation treatment can be assessed.
The wellbore characteristics affecting completion con-
figuration or component selection are best summarized
by reviewing the drilling, evaluation and pre-completion
activities (Fig. 6).
Fig. 6. Wellbore construction
Drilling
Hole size
Depth
Deviation
Well path
Formation damage
Pre-completion
Casing schedules
Primary cementing
Pre-completion stimulation
WELLBORE CONSTRUCTION
Evaluation
Logging
Coring
Testing
Fluid sampling
CONFIDENTIALITY
This manual section is a confidential document which must not be copied in whole or in part or
discussed with anyone outside the Schlumberger organisation.
Completion Assembly and Installation
This stages marks the beginning of what is commonly
perceived as the \u201ccompletion program\u201d. It is the intent of
this manual to enlighten readers as to the true and
necessary extent of the \u201ccompletion program\u201d. As has
been demonstrated, considerable preparation, evalua-
tion and design work has been completed before the
completion tubulars and components are selected.
With all design data gathered and verified, the completion
component selection, assembly and installation process
commences. This phase carries obvious importance since
the overall efficiency of the completion system depends
on proper selection and installation of components.
A \u201cvisionary\u201d approach is necessary since the influence of
all factors must be considered at this stage, i.e., factors
resulting from previous operations or events, plus an
allowance, or contingency, for factors which are likely or
liable to effect the completion system performance in the
future.
The correct assembly and installation of components in
the wellbore is as critical as the selection process by which
they are chosen.
This is typically a time at which many people and re-
sources are brought together to perform the operation.
Consequently, the demands brought by high, and mount-
ing daily charges imposes a sense of urgency which
requires the operation be completed without delay.
To ensure the operation proceeds as planned, it is essen-
tial that detailed procedures are prepared for each stage
of the completion assembly and installation. The com-
plexity and detail of the procedure is largely dependent on
the complexity of the completion.
In general, completion components are broadly catego-
rized as follows.
\u2022 Primary completion components
\u2022 Ancillary completion components
Primary completion components are considered essen-
tial for the completion to function safely as designed. Such
components include the wellhead, tubing string, safety
valves and packers. In special applications, e.g., artificial
lift, the components necessary to enable the completion
system to function as designed will normally be consid-
ered primary components.
Fig. 7. Completion assembly and installation.
Primary Components
Wellhead
Xmas tree
Tubing
Packer
Safety valve
Ancillary Components
Circulating devices
Nipples
Flow couplings
Injection mandrels
Tubing seal assembly
COMPLETION ASSEMBLY AND INSTALLATION
Completion Fluids
Completion fluid
Packer fluid
Perforating fluid
Kick-off fluid
CONFIDENTIALITY
This manual section is a confidential document which must not be copied in whole or in part or
discussed with anyone outside the Schlumberger organisation.
Ancillary completion components enable a higher level of
control or flexibility for the completion system. For ex-
ample, the installation of nipples and flow control devices
can allow improved control.
Several types of device, with varying degrees of impor-
tance, can be installed to permit greater flexibility of the
completion. While this is generally viewed as beneficial, a
complex completion will often be more vulnerable to
problems or failure, e.g., due to leakage.
The desire for flexibility in a completion system stems from
the changing conditions over the lifetime of a well, field or
reservoir. For example, as the reservoir pressure de-
pletes, gas injection via a side-pocket mandrel may be
necessary to maintain optimized production levels.
A significant fluid sales and service industry has evolved
around the provision of completion fluids. Completion
fluids often require special mixing and handling proce-
dures, since (i) the level quality control exercised on
density and cleanliness is high, and (ii) completion fluids
are often formulated with dangerous brines and inhibitors.
The ultimate selection of completion components and
fluids should generally be made to provide a balance
between flexibility and simplicity.
The completion component selection factors are best
summarized by reviewing the primary and ancillary com-
ponents, and installation procedures (Fig. 7).
Initiating Production
The three stages associated with this phase of the comple-
tion process include (Fig. 8 and 9).
\u2022 Kick-off
\u2022 Clean up
\u2022 Stimulation
The process of initiating flow and establishing communi-
cation between the reservoir and the wellbore is obviously
closely associated with perforating operations. If the well
is to be perforated overbalanced, then the flow initiation
and clean up program may be dealt with in separate
procedures. However, if the well is perforated in an
underbalanced condition, the flow initiation and clean up
procedures must commence immediately upon perfora-
tion.
The benefits of underbalanced perforating are well docu-
mented and the procedure is now conducted on a routine
basis. While the reservoir/wellbore pressure differential
may be sufficient to provide an underbalance at time of
perforation, the reservoir pressure may be insufficient to
cause the well to flow after the pressure has equalized.
Adequate reservoir pressure must exist to displace the
fluids from within the production tubing if the well is to flow
unaided. Should the reservoir pressure be insufficient to
achieve this, measures must be taken to lighten the fluid
Clean-up Program
Initial flowrate and
rate of increase
Evaluation program
Test\u2013treat\u2013test
PRODUCTION INITIATION
Inducing Flow
Gas lift
Nitrogen kick-off
Light-fluid circulation
Using completion components
or coiled tubing
Fig. 8. Production initiation.
CONFIDENTIALITY
This manual section is a confidential document which must not be copied in whole or in part or
discussed with anyone outside the Schlumberger organisation.
Near Wellbore and Reservoir Matrix
Matrix acidizing
Hydraulic fracturing
Non-acid treatments
STIMULATION
Wellbore and Perforations
Wellbore clean-up
Perforating acid
Perforation